Stent configurations

ABSTRACT

Improved stent configurations exhibiting limited recoil, resistance to compression and improved longitudinal flexibility.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation of U.S. application Ser. No.08/947,620 filed Oct. 9, 1997, the contents of which are incorporatedherein in their entirety by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to stents of improved configuration.

[0004] 2. Brief Description of the Prior Art

[0005] Stents are radially expandable endoprosthesis which are typicallyintravascular implants capable of being implanted transluminally andenlarged radially after being introduced percutaneously. They have alsobeen implanted in urinary tracts and bile ducts. They are used toreinforce body vessels and to prevent restenosis following angioplastyin the vascular system. They may be self-expanding or expanded by aninternal radial force, such as when mounted on a balloon.

[0006] In the past, stents have been generally tubular but have beencomposed of many configurations and have been made of many materials,including metals and plastic. Ordinary metals such as stainless steelhave been used as have shape memory metals such as Nitinol and the like.Stents have also been made of biodegradable plastic materials. Suchstents have been formed from wire, tube stock, etc.

SUMMARY OF THE INVENTION

[0007] This invention provides new configurations of the cells making upstents which may be adapted to all of the various types of prior artstents described above and/or known previously in the art. There arenumerous advantages to the new configurations. The configurations of theinvention limit recoil and add resistance to compression for an expandedstent, among other things. Other configurations than cylindrical arecontemplated, e.g., square, triangular octagonal, etc. The stents ofthis invention are longitudinally flexible and expandable.

BRIEF DESCRIPTION OF THE FIGURES

[0008]FIG. 1 is a flat plan view of an embodiment of the stentconfiguration of the invention in the unexpanded condition;

[0009]FIG. 1a is a fragmentary plan similar to FIG. 1 showing astaggered arrangement of the cells making up a stent;

[0010]FIG. 1b and 1 c show cells similar to FIG. 1 and 1 a in differentarrangements and with differing interconnection;

[0011]FIG. 2 is an end view of a stent of FIG. 1 according to theinvention in its normal tubular unexpanded condition;

[0012]FIG. 3 is a detail view of a portion of FIG. 1, as indicated;

[0013]FIG. 4 is a view of the stent of FIGS. 1 and 2 expanded on aballoon;

[0014]FIG. 5 is another stent embodiment of the invention similar inview to FIG. 1 showing the flat plan of the stent in the unexpandedconfiguration;

[0015]FIG. 6 is a detail view of a portion of FIG. 5, as indicated;

[0016]FIG. 7 is a showing of the stent of FIG. 4 expanded on a balloon;

[0017]FIG. 8 is a flat plan similar to FIGS. 1 and 5 showing anotherstent embodiment in the unexpanded condition;

[0018]FIG. 8a is a plan view in fragment showing a variation of the cellconfiguration shown in FIG. 8;

[0019]FIG. 9 is a detail view of a portion of FIG. 8, as indicated;

[0020]FIG. 10 is a showing of the stent of FIG. 8 expanded on a balloon;

[0021]FIG. 11 is a flat plan similar to FIGS. 1, 5, and 8 showing yetanother stent embodiment in the unexpanded condition;

[0022]FIG. 12 is a detail view of a portion of FIG. 11, as indicated;

[0023]FIG. 13 is a view of the stent of FIG. 11 on an unexpanded balloondemonstrating its flexibility in the unexpanded condition;

[0024]FIG. 14 is a showing of the stent of FIG. 11 expanded on aballoon;

[0025]FIG. 15 is a flat plan similar to FIGS. 1, 5, 8, and 11 showingyet another stent embodiment in the unexpanded condition;

[0026]FIG. 16 is a detail view of a portion of FIG. 15, as indicated;

[0027]FIG. 17 is a showing of the stent of FIG. 15 expanded on aballoon;

[0028]FIG. 18 is a flat plan similar to FIGS. 1, 5, 8, 11 and 15 showingstill another stent embodiment in the unexpanded condition;

[0029]FIG. 19 is a detail view of a portion of FIG. 18, as indicated;

[0030]FIG. 20 is a flat plan view similar to FIGS. 1, 5, 8, 11, 15 and18 showing yet another stent embodiment in the unexpanded condition;

[0031]FIG. 21 is a detail view of a portion of FIG. 20, and

[0032]FIG. 22 is a flat plan view of another embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] A preferred embodiment of a generally cylindrical stent 10according to the invention is illustrated in FIGS. 1-4. It comprises ametal tube as shown in FIGS. 2 and 4, such as nitinol or stainless steelpreferably, which has been etched or preferably laser cut to theconfiguration shown in the flat plan view of FIG. 1. An enlarged detailof FIG. 1 is shown in FIG. 3. The configuration is made up of a seriesof curvilinear expansion cell elements generally indicated at 12 (seedarkened example in FIG. 3 for clarity) having relatively wide endportions 14 joined by relatively narrow center, portions 16. Cells 12are arranged longitudinally as shown in FIG. 1 end to end with respectto the longitudinal axis of the stent 10 and in substantially parallelrows as also shown in FIG. 1. A plurality of longitudinally extendingelongate support members 18 are included, one each being disposedbetween adjacent rows of cells 12. Also, a plurality ofcircumferentially extending support members 19, preferably substantiallynormal to support members 18 are also positioned between the rows ofcells 12 to intersect portions of the support members 18 and tointerconnect them to the narrow center portions 16 of cells 12. As canbe seen in FIG. 1a, cells 12 may also be arranged in a staggeredarrangement. FIGS. 1b and 1 c demonstrate different arrangements andinterconnections for cells 12.

[0034] When the stent is expanded, as shown in FIG. 4, on a balloon 20the cells 12 take on a new configuration as shown, the members making upthe stent being indicated by the same numbers as used in FIG. 1 and FIG.3. Again, one cell is shown darkened for clarity.

[0035] Referring now to FIGS. 5-7, another stent embodiment generallyindicated at 22 of the invention is shown. In this embodiment, as seenin FIGS. 5 and 6, expansion cells 24, best seen in the detail of FIG. 6and indicated by darkened portion, have relatively wide end portions 26,best seen in FIG. 6, and narrow center portions 28 and are arranged endto end in longitudinal rows as described with respect to the firstembodiment. Adjacent end portions 26 are interconnected by pairs oflongitudinal support members in the form of segments 30 which havecurved end portions 32. Circumferential extending segments 34 extendbetween rows of cells 24 to interconnect the narrow center portions 28.

[0036] Upon radial expansion of the stent, as on a balloon 20 forexample, its configuration changes by deformation force in thedirections shown by the arrows in FIG. 6 to that configuration shown inFIG. 7. The elements indicated in FIG. 7 are identified by the samenumbers indicated for similar elements in FIGS. 5 and 6.

[0037]FIGS. 20 and 21 show a configuration somewhat similar to that ofFIGS. 5-7 but without interconnecting elements 28.

[0038] Referring now to FIGS. 8-10, another stent embodiment of theinvention is shown and generally indicated at 40. Again, as seen inFIGS. 8 and 9, expansion cells 42 (example darkened for clarity) haverelatively wide end portions 44 and narrow center portions 46. The endportions include inwardly extending loop portions 48. Cells 42 arearranged end to end in longitudinal rows as in the precedingembodiments. Adjacent end portions 44 are interconnected by pairs oflongitudinal support member segments 50 which have curved end portions52. Circumferentially extending segments 54 extend between rows of cells42 to interconnect the narrow center portions 46 of the cells. FIG. 8ashows a variation in shape for cells 42.

[0039] Upon radial expansion of the stent upon a balloon 20, theconfiguration changes to that shown in FIG. 10. The arrows show thedirection of force of deformation upon expansion.

[0040] Referring now to FIGS. 11 and 12, still another embodiment of astent 60 is shown. Again, as shown in FIGS. 11 and 12, expansion cells62 (example darkened for clarity) have relatively wide end portions 64having a slight inward bend 65 to them and narrow center portions 66.Cells 62 are arranged end to end in longitudinal rows as in thepreceding embodiments. Adjacent end portions 64 are interconnected bypairs of longitudinal support member segments 68 which have curved endportions 70. Circumferentially extending segments 72 extend between rowsof cells 62 to interconnect the narrow center portions 66 of the cells.

[0041] Reference to FIG. 13 will show the inherent flexibility of thestents of this invention.

[0042] Upon radial expansion of the stent upon a balloon 20, theconfiguration changes to that shown in FIG. 14.

[0043] Referring now to FIGS. 15 and 16, yet another embodiment of astent 80 is shown in a configuration quite similar to that of FIGS.11-14 but with an added circumferentially extending structural element81. Again, as best seen in FIG. 16, expansion cells 82 (examplesdarkened for clarity) have relatively wide end portions 84 having aslight inward bend 85 to them and narrow center portions 86. Cells 82are arranged end to end in longitudinal rows as in the precedingembodiments. Adjacent end portions 84 are interconnected by pairs oflongitudinal support member segments 88 which have curved end portions90. Circumferentially extending segments 92 extend between rows of cells82 to interconnect the narrow center portions 86 of the cells.Circumferentially extending segments 81 interconnect pairs of supportmember segments 88.

[0044] Upon radial expansion of the stent on a balloon 20, theconfiguration changes to that shown in FIG. 17.

[0045] Referring now to FIGS. 18 and 19, still another embodiment of astent configuration 100 is shown. As before this embodiment is similarto that of FIGS. 11-12 except that the circumferentially extendingsegments 101 are arranged differently than those identified in FIGS.11-12 as 72. In this embodiment the circumferentially extending members101 extend between the adjacent ends of adjacent cells 103 (examplesdarkened for clarity) to interconnect the top of one end to the bottomof the adjacent end and the members 101 have a slight curve or bend 105in their length. The other members are all similarly numbered as in thepreceding Figures.

[0046]FIG. 22 shows yet another embodiment of a stent comprised of cells120 having interconnecting circumferential extending members 122. Thecells have common sides or end members 124 and are arranged in groups toform bands 126 which are interconnected by joined cells 128.

[0047] While this invention may be embodied in many different forms,there are described in detail herein specific preferred embodiments ofthe invention. This description is an exemplification of the principlesof the invention and is not intended to limit the invention to theparticular embodiments illustrated.

[0048] The above Examples and disclosure are intended to be illustrativeand not exhaustive. These examples and description will suggest manyvariations and alternatives to one of ordinary skill in this art. Allthese alternatives and variations are intended to be included within thescope of the attached claims. Those familiar with the art may recognizeother equivalents to the specific embodiments described herein whichequivalents are also intended to be encompassed by the claims attachedhereto.

What is claimed is as follows:
 1. A stent of generally cylindrical shapeand having a longitudinal axis comprising interconnected cylindricalbands of separate regularly arranged curvilinear bodies, the curvilinearbodies providing individual closed expansion cells, the cells havingrelatively wide end portions joined by a relatively narrow centerportion and being arranged end to end longitudinally with respect to thelongitudinal axis of the stent, the curvilinear bodies beinginterconnected by one or more interconnecting elements which extend fromone curvilinear body to another.
 2. The stent of claim 1 in an expandedstate
 3. The stent of claim 1 in the unexpanded state.
 4. The stent ofclaim 1 wherein the curvilinear bodies are also arranged in longitudinalrows with respect to the longitudinal axis of the stent.
 5. The stent ofclaim 4 wherein the longitudinal rows of curvilinear bodies aresubstantially parallel.
 6. The stent of claim 4 wherein the rows ofcells are substantially parallel and the cells are in alignmentcircumferentially.
 7. The stent of claim 1 wherein cylindrical bands areinterconnected by interconnecting elements which extend from like sidesof adjacent curvilinear bodies in adjacent bands.
 8. The stent of claim1 wherein adjacent cylindrical bands are interconnected byinterconnecting elements which extend from opposite sides of thecurvilinear bodies in adjacent bands.
 9. The stent of claim 1 whereinthe interconnecting elements are rotationally interconnected to thecurvilinear bodies.
 10. A stent of generally cylindrical shape andhaving a longitudinal axis comprising interconnected cylindrical bandsof separate regularly arranged curvilinear bodies, the curvilinearbodies providing individual closed expansion cells, the cells havingrelatively wide end portions joined by a relatively narrow centerportion and being arranged end to end longitudinally with respect to thelongitudinal axis of the stent, the curvilinear bodies beinginterconnected by one or more rotational elements which extend from onecurvilinear body to another, each rotational element having a first endand a second end, which are capable of rotating.
 11. The stent of claim10 wherein the rotational elements interconnect adjacent curvilinearbodies oriented longitudinally and circumferentially relative to eachother.
 12. A stent of generally cylindrical shape and having alongitudinal axis comprising: a plurality of curvilinear bodiesproviding closed expansion cells, the cells being formed of relativelywide end portions and narrow center portions and being arranged end toend longitudinally along the longitudinal axis of the stent; rotationalinterconnecting elements interconnecting the end portions of adjacentcells, each rotational element having a first end and a second end,which are capable of rotating; circumferentially extending membersextending between cells of adjacent rows and interconnecting the cellsat the narrow portions.
 13. The stent of claim 12 wherein each endportion of the closed expansion cells has a top and a bottom, therotational elements extending between adjacent cell end portionsinterconnecting the top of one cell end to the bottom of another. 14.The stent of claim 13 wherein the bodies are also arranged end to end insubstantially parallel longitudinal rows.